If you are using Google Chrome or Firefox, you can install the free Stylish browser extension (which I did not write and have no interest in) and the custom stylesheet I created for Ancestry's web site:
http://userstyles.org/
My custom style is here:
http://userstyles.org/styles/93480/ancestry-com-wider-tree
It replaces the photos with blue or pink boxes, increases the font sizes dramatically, and aligns the text to be easier to read.
This has only been tested with Chrome, but should theoretically work in Firefox as well.
Caveat: some longer names are cut off on the right, a consequence of using a larger font with the same box sizes. I chose a font (Trebuchet MS) that balanced relatively skinny characters with good readability. A few other common fonts like Arial Narrow would allow more letters, but at the expense of readability and general ugliness.
This tweak is not supported by or endorsed by Ancestry.com, and I don't work for them.